A Surprising Gift From The Moon

A chunk of the moon that landed on Earth as a meteorite contains a new mineral, which scientists have named after a researcher who years ago predicted the unusual process that formed the material.

Grains of the material, made of iron and silicon, were found in pieces of a meteorite that was discovered in Oman on the Saudi peninsula, said Lawrence A. Taylor of the University of Tennessee, a member of the research team that reported the find.

The process that led to the material's formation on the moon "is much different than anything we can imagine on Earth," Taylor explained.

Small meteorites that would burn up in an atmosphere like Earth's can crash into the moon because of its lack of an atmosphere. The mineral was found in a piece of the moon that had been large enough to make it through the Earth's atmosphere without being destroyed.

When that happens, Taylor explained, the impact creates heat that melts some of the rocks and forms a vapor that is deposited on nearby materials.

The process and discovery of the new material is reported in this week's issue of Proceedings of the National Academy of Sciences.

Some iron-silicon minerals form on Earth, sometimes as a result of lightning strikes, but new mineral is a different combination, Taylor said. Hapkeite has the chemical formula Fe2Si, indicating the presence of two atoms of iron to one of silicon.

The researchers named the new mineral hapkeite after Bruce Hapke of the University of Pittsburgh, who 30 years ago predicted the process that forms this mineral.

"I told them so," said an amused Hapke, who added: "It's quite an honor."

He said he developed the theory to explain weathering of surface materials in space, a process that darkens the moon's surface.

Weathering on Earth creates soil through the action of water, oxygen and organic processes. That can't happen on a place without water or an atmosphere, so the darkening and breaking down of the surface rocks had to be explained in another way.

Benton C. Clark, a weathering expert at Lockheed Martin Corp., said the process of forming the moon mineral seems plausible, but stressed that it needs to be defined as "space weathering," which would be unlike weathering on Earth.

"Naming a mineral after the outstanding scientist Bruce Hapke is a fitting tribute," he said.

Robert Craddock, science adviser for the Smithsonian Institution's undersecretary for science, said the paper explains some of the spectral measurements researchers read when they study airless planets. Measurements of the spectrum of reflected light are used to help determine the presence of minerals.

The newly found mineral, he added, is one of a number of minerals predicted as possible a result of space weathering.